This application relates to a cooled turbine component, such as a turbine blade.
Gas turbine engines are known, and include a plurality of sections mounted along a serial flow path. A fan directs air into a compressor where it is compressed. The compressed air is delivered into a combustion section. In the combustion section the compressed air is mixed with fuel and combusted. Products of combustion pass downstream over turbine rotors. The turbine rotors are driven by the products of combustion, and drive the fan and compressor sections. Typically, the turbine includes a plurality of rotors each having circumferentially spaced blades that are removable from the rotor. In addition, stationary vanes are positioned adjacent to the turbine rotors.
The products of combustion are hot, and thus the rotor blades and vanes are exposed to high temperatures. One method to address the high temperatures experienced by the blades is the use of internal air cooling passages in the blade airfoil. The design of turbine blades includes optimizing air cooling passages. One standard type of passage is a serpentine path. In a serpentine path, cooling air is directed radially outwardly from an inner root of the blade and toward an outer tip of the blade. The air reaches the outer tip of the blade and circulates back toward the root, eventually returning again back radially outwardly. Another type of cooling air passage directs air along a length of the airfoil, and then direct the air outwardly to openings at a trailing edge. This type of cooling air passage is often utilized with a plurality of metering openings which meter the amount of air being delivered to trailing edge skin cooling openings.
In the prior art the cooling of the radially outermost portion of the airfoil at the trailing edge has proven problematic. As one example, the cooling air path delivering air to the trailing edge has delivered much of its air outwardly for skin cooling before reaching the radially outer portion of the trailing edge. As such, cooling is not as effective as it is at radially inner locations. Thus, in the prior art additional cooling has been delivered by a tip flag including a divider directing some air from a radially outer part of the serpentine path to the radially outer portion of the traveling edge. This air provides additional cooling to the area in question. However, additional cooling is still necessary. One further refinement of the tip flag concept is to provide trip strips on the walls of the blade along the tip flag path. These tip strips create turbulence in the airflow, and thus increase cooling. Even so, there are still problems with spallation of external coatings, burning, and oxidation at the area in question.